Enhanced Uplink (EU) is one of the major features in third generation partnership project (3GPP) frequency division duplex (FDD) systems. EU offers a peak data rate of 5.76 Mbps. In order to support EU operation, several downlink physical channels are provided to transmit control information. One of the downlink physical channels is the E-HICH.
FIG. 1 is a block diagram of a conventional wireless communication system 100 which supports EU. The system 100 comprises a wireless transmit/receive unit (WTRU) 102, a Node-B 104 and a radio network controller (RNC) 106. The RNC 106 controls overall E-DCH operation by configuring E-DCH parameters for the Node-B 104 and the WTRU 102, such as initial transmit power level, maximum allowed transmit power or available channel resources per Node-B. Between the WTRU 102 and the Node-B 104, an E-DCH 108, an E-DCH dedicated physical control channel (E-DPCCH), an E-DCH absolute grant channel (E-AGCH) 112, an E-DCH relative grant channel (E-RGCH) 114 and an E-HICH 116 are established for supporting E-DCH operations.
For E-DCH transmissions, the WTRU 102 sends triggered scheduling information, (also known as a rate request), for the logical channels which a radio resource control (RRC) determines that reporting is needed to be made to the Node-B 104 via the E-DCH 108. The Node-B 104 sends a scheduling grant to the WTRU 102 via the E-AGCH 112 or the E-RGCH 114. After E-DCH radio resources are allocated for the WTRU 102, the WTRU 102 transmits uplink (UL) data via the E-DCH 108. In response to E-DCH or E-DPCCH transmissions, the Node-B 104 sends an acknowledgement (ACK) or a non-acknowledgement (NACK) message for H-ARQ operation via the E-HICH 116.
The E-HICH 116 is a very important channel for fast transmission and retransmission of E-DCH data. A reliable detection of the E-HICH transmission is therefore critical for EU operation. A successful detection and decoding of the E-HICH transmission significantly affects the performance of data transmissions for the E-DCH, and affects the performance of the entire EU systems. Therefore, it is desirable to have a method and apparatus for efficiently detecting and decoding E-HICH transmissions.